Book 12: 《顏淵》 Yan Yuan
《顏淵》 Passage 12.23
子貢問友。子曰:「忠告而善道之,不可則止,無自辱焉。」
Legge Translation (1861)
Zigong asked about friendship. The Master said: "Faithfully admonish your friend, and skillfully lead him on. If you find him impracticable, stop. Do not disgrace yourself."